The business and culture of our digital lives, from the L.A. Times

White iPhone or black, it doesn't matter to T-Mobile USA. The wireless carrier is going after iPhone users -- i.e. AT&T and Verizon subscribers -- in a publicity stunt involving Apple's smartphone that may or may not cost the company thousands of dollars to pull off.

"Hey Seattle - $1,000 says the Galaxy S 4G is faster than your iPhone. Are you up to the challenge?" T-Mobile said in a message on Twitter on Wednesday.

T-Mobile has laid out a promotion in which iPhone owners will pit their handsets against the Samsung Galaxy S 4G to see which phone is fastest at downloading files in a speed test T-Mobile has set up.

If an iPhone owner's phone proves faster, then T-Mobile will will pay out $1,000 in the form of a check (that will take six to eight weeks to arrive).

"T-Mobile has been making significant investments in our network, which is why we are confident our smartphone can beat the iconic iPhone, which runs on Verizon's and AT&T's 3G networks," T-Mobile said in a blog post. "This speed challenge will give Seattle area iPhone users the chance to see for themselves why we are so excited about T-Mobile's 4G network and why now is a great time to be a T-Mobile customer."

Both AT&T and Verizon will start selling the white iPhone 4 this weekend as well.

The promotion is only being offered at 10 T-Mobile stores in Seattle -- and so far nowhere else -- this Friday through Sunday. T-Mobile officials weren't available on Wednesday to say why the promotion is being offered only in Seattle.

The speed tests are limited to one per person, and the iPhone owners must be at least 18 years old and a resident of the U.S.

The iPhones used in the tests can only perform the tests using AT&T's or Verizon's wireless networks, not Wi-Fi, and participants have to agree to complete a T-Mobile survey, which likely will include forking over some personal info -- name, address, etc.

The tests use a "free speed test Application specified by T-Mobile," the company said in the blog post.

"Speed challenge consists of three tests of the Galaxy S 4G versus the iPhone based solely on download speeds as measured by the Application; participants will be eligible to receive $1,000 if their iPhones are faster in two out of the three tests," T-Mobile said.